Data writing device

ABSTRACT

A data writing device includes a roller configured to convey a label including a radio tag along a predetermined path, a reader/writer configured to wirelessly communicate with the radio tag, and a controller configured to control the roller to convey the label and control the reader/writer to acquire a plurality of radio wave intensities from the radio tag at different positions along the predetermined path as the label is conveyed, and determine one of the different positions along the predetermined path at which the radio wave intensities are equal to or greater than a threshold value as a writing position for the radio tag.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2018-016619, filed on Feb. 1, 2018 theentire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a data writing device.

BACKGROUND

There is a data writing device for writing data into a radio tag such asa radio frequency identifier (RFID) tag. Such a data writing deviceconveys a label including the radio tag and writes data into the radiotag at a predetermined position.

However, in the related art, the data writing device is controlled towrite the data at the predetermined position regardless of the actualintensity of the radio wave. Thus, in the data writing device of therelated art, the data may be written into the radio tag at a positionwhere the radio wave condition is not good.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a data writing device according to afirst embodiment;

FIG. 2 is a view showing a print head according to the first embodiment;

FIG. 3 is a view showing a label roll paper according to the firstembodiment;

FIG. 4 is a view showing an example of the label roll paper;

FIG. 5 is a view showing a label according to the first embodiment;

FIG. 6 is a graph of the intensity of a radio wave from a radio tagaccording to the first embodiment;

FIG. 7 is a flowchart of operation performed by the data writing device;

FIG. 8 is a flowchart of operation performed by the data writing device;

FIG. 9 is a graph showing the intensity of a radio wave from a radio tagaccording to a second embodiment; and

FIG. 10 is a flowchart of operation performed by a data writing deviceaccording to the second embodiment.

DETAILED DESCRIPTION

An embodiment provides a data writing device capable of writing data ata position where the sensitivity of a radio wave from a radio tag ishigh.

In general, according to one embodiment, a data writing device includesa roller configured to convey a label including a radio tag along apredetermined path, a reader/writer configured to wirelessly communicatewith the radio tag, and a controller configured to control the roller toconvey the label and control the reader/writer to acquire a plurality ofradio wave intensities from the radio tag at different positions alongthe predetermined path as the label is conveyed, and determine one ofthe different positions along the predetermined path at which the radiowave intensities are equal to or greater than a threshold value as awriting position for the radio tag.

Hereinafter, embodiments will be described in detail with reference tothe drawings.

First Embodiment

First, a first embodiment will be described.

The data writing device according to the first embodiment stores data ina radio tag. For example, the data writing device stores a labelincluding the radio tag. The data writing device conveys the label to apredetermined position and stores the data in the radio tag of thelabel. In addition, the data writing device stores predetermined data inthe radio tag based on operation input by an operator or the like. Inaddition, the data writing device prints a predetermined image on thelabel. The data writing device conveys the label, on which the image isprinted, and discharges the label to the outside.

FIG. 1 is a block diagram showing the configuration example of a datawriting device 1. As shown in FIG. 1, the data writing device 1 includesa controller 11, a display device 12, an input device 13, an interface14, a memory 15, a reader/writer 16, an antenna 17, a print head drivecircuit 18, a print head 19, a motor driver 20, a motor 21, a roller 22,a sensor circuit 23 and a mark sensor 24.

The controller 11, the display device 12, the input device 13, theinterface 14, the memory 15, the reader/writer 16, the print head drivecircuit 18, the motor driver 20 and the sensor circuit 23 are connectedto one another through a data bus or the like.

The reader/writer 16 and the antenna 17 are electrically connected toeach other. The print head drive circuit 18 and the print head 19 areelectrically connected to each other. The motor driver 20 and the motor21 are electrically connected to each other. The motor 21 and the roller22 are physically connected. The sensor circuit 23 and the mark sensor24 are electrically connected to each other.

In addition, the data writing device 1 may include other components inaddition to the components shown in FIG. 1 as necessary or a specificcomponent of the data writing device 1 may be excluded.

The controller 11 controls the entire data writing device 1. Thecontroller 11 includes a processor 111 or the like.

The processor 111 controls operation of the controller 11. That is, theprocessor 111 controls the entire data writing device 1. The processor111 may include an internal memory, various types of interfaces, and thelike. The processor 111 performs various processes by executing aprogram pre-stored in the internal memory or the memory 15.

In addition, some of the various types of functions performed by theprocessor 111 may be realized by a hardware circuit. In this case, theprocessor 111 controls the function executed by the hardware circuit.

The display device 12 displays a variety of information by control ofthe processor 111. For example, the display device 12 includes a liquidcrystal monitor.

The input device 13 receives input of various operations from theoperator. The input device 13 transmits a signal indicating the receivedoperation to the processor 111. For example, the input device 13includes a keyboard, a numeric keypad and a touch panel. In addition, ifthe input device 13 includes the touch panel or the like, the inputdevice may be formed integrally with the display device 12.

The interface 14 is an interface for transmitting or receiving data toor from an external device. For example, the interface 14 transmits orreceives data to or from the external device through a network such as alocal area network (LAN). The interface 14 may be an interfacesupporting USB connection.

The memory 15 is a rewritable non-volatile memory. The memory 15 is, forexample, include, an SSD, an HDD or the like. In addition, the memory 15may store a program executed by the processor 111, control data and thelike.

The reader/writer 16 is a device for performing wireless communicationwith a radio tag 44 through the antenna 17. The reader/writer 16 readsidentification information (for example, an electronic product code(EPC)) or the like of the radio tag 44 by a radio wave from the radiotag 44. In addition, the reader/writer 16 acquires the intensity of theradio wave from the radio tag 44. In addition, the reader/writer 16stores predetermined data in the radio tag 44 based on a signal from thecontroller 11.

The antenna 17 allows the reader/writer 16 to perform wirelesscommunication with the radio tag 44. For example, the antenna 17 isprovided to be adjacent to a conveyance path, where the radio tag 44 isconveyed. In addition, the antenna 17 may be a directional antennahaving directivity in the conveyance path.

The print head drive circuit 18 controls driving of the print head 19according to a signal from the controller 11. For example, the printhead drive circuit 18 transmits power or a control signal to the printhead 19.

The print head 19 prints an image on a label 43 including the radio tag44 based on control of the print head drive circuit 18. For example, theprint head 19 includes an inkjet head for ejecting ink droplets. Theprint head 19 may print a monochrome image on the label 43 or print acolor image on the label 43.

The motor driver 20 controls driving of the motor 21 according to asignal from the controller 11. For example, the motor driver 20transmits power or a control signal to the motor 21.

The motor 21 drives the roller 22 based on control of the motor driver20. For example, the motor 21 is a stepping motor or the like.

The roller 22 rotates by driving force from the motor 21. The roller 22rotates to convey the label 43 in a predetermined direction.

The sensor circuit 23 controls driving of the mark sensor 24 accordingto a signal from the controller 11. For example, the sensor circuit 23transmits power or a control signal to the mark sensor 24.

The mark sensor 24 reads a mark 45 formed on a label roll paper 41. Themark sensor 24 transmits a predetermined signal to the sensor circuit 23when the mark 45 is read. For example, the mark sensor 24 is an opticalsensor or the like.

FIG. 2 is a view showing a positional relationship of the antenna 17 andthe like. As shown in FIG. 2, the roller 22 includes rollers 22 a and 22b. The roller 22 a and the roller 22 b are formed at a predeterminedinterval. The label roll paper 41 is conveyed from the side of theroller 22 a to the side of the roller 22 b. Here, the side of the roller22 a is an upstream side and the side of the roller 22 b is a downstreamside.

The rollers 22 a and 22 b include two rollers for holding and conveyingthe label roll paper 41.

The mark sensor 24 is formed at the downstream side of the roller 22 a.The mark sensor 24 detects the mark 45 on the back surface of the labelroll paper 41.

The antenna 17 is formed at the downstream side of the mark sensor 24.The antenna 17 is formed at a position facing the mark sensor 24. Thatis, the antenna 17 is formed to be adjacent to the surface of the labelroll paper 41.

The print head 19 is formed at the downstream side of the antenna 17.The print head 19 is formed to be in contact with the surface of thelabel roll paper 41. That is, the print head 19 forms an image on thesurface of a label 43.

The roller 22 b is formed at the downstream side of the print head 19.

Next, the label roll paper 41 will be described. FIG. 3 shows an exampleof the surface of the label roll paper 41. In addition, FIG. 4 shows anexample of the back surface of the label roll paper 41.

The label roll paper 41 is a roll of label paper including a pluralityof labels 43 in a row. The label roll paper 41 is formed to extend inparallel with the long side of the label 43.

The label roll paper 41 includes a mount 42 and a label 43.

The mount 42 supports the plurality of labels 43 at a predeterminedinterval in a row. For example, the mount 42 is partially connected tothe label 43 to support the label 43. For example, the mount 42 includesa material such as plastic or vinyl.

The label 43 is a medium including the radio tag 44 therein. The label43 is formed in a rectangular shape. The label 43 is formed bylaminating a plurality of layers. The label 43 includes the radio tag 44between the plurality of layers. For example, the label 43 includes amaterial such as paper, plastic or vinyl. The label 43 may include thesame material as the mount 42 or may include a material different fromthat of the mount 42.

In addition, the label roll paper 41 includes the mark 45 on the backsurface. The mark 45 is used by the data writing device 1 to recognizethe position of the label 43. The mark 45 is attached to each label 43.Here, the mark 45 is attached to a start point of the label 43.

Next, the label 43 will be described. FIG. 5 shows an example of thelabel 43.

As shown in FIG. 5, the label 43 includes the radio tag 44, a printregion 431 and the like. In addition, the label may include the othercomponents in addition to the components shown in FIG. 5 as necessary ora specific component may be excluded.

The radio tag 44 is disposed at a predetermined position of the label43. In the example shown in FIG. 5, the radio tag 44 is disposed on theleft side of the label 43. In addition, the radio tag 44 may be disposedon the right side or the center of the label 43. The position where theradio tag 44 is disposed is not limited to a specific configuration.

The radio tag 44 is embedded between the plurality of layers configuringthe label 43. In addition, at least one radio tag 44 is embedded intoone label 43. The radio tag 44 is wirelessly written from an externaldevice with predetermined data or wirelessly transmits predetermineddata to the external device.

As shown in FIG. 5, the radio tag 44 includes a chip 441 and an antenna442.

The chip 441 controls the entire radio tag 44. For example, the chip 441includes a control unit, a memory, a communication interface and thelike.

The control unit has a function for controlling overall operation of thechip 441. The control unit may include an internal cache memory, varioustypes of interfaces, and the like. For example, the control unitperforms various processes by data stored in the internal memory or thememory. The control unit may include a processor and the like. Inaddition, the control unit may include hardware such as a sequencer.

The memory is a non-volatile memory in which data may be written. Thememory stores a variety of data based on operation of the control unit.In addition, the memory may store data for preliminary control accordingto usage of the radio tag 44. In addition, the memory may temporarilystore data which is being processed by the control unit. In addition,the memory may be a non-volatile memory in which data may be rewritten.

The communication interface is an interface for communicating with anexternal device through the antenna 442. The communication interface mayinclude a power supply for supplying power received from the externaldevice.

The antenna 442 is an antenna for wirelessly communicating with theexternal device. The antenna 442 is also used to receive power suppliedfrom the external device. For example, the antenna 442 may be formed ina predetermined region in a mesh shape. In addition, the antenna 442 maybe formed in a predetermined region in a circular shape.

The radio tag 44 is activated (e.g., becomes an operable state) byreceiving power supplied from the external device in a non-contactmanner. The radio tag 44 receives a radio wave from the external devicethrough the antenna 442 as a communication interface and amodulation-demodulation circuit. The radio tag 44 generates andactivates operation power and an operation clock by the power supplydriven by the radio wave.

When the radio tag 44 is activated, the chip 441 can perform datacommunication with the external device through the antenna 442. Forexample, the chip 441 receives an access password or the like from suchas the reader/writer 16 through the antenna 442 and establishescommunication with the reader/writer 16. In addition, the chip 441transmits and receives predetermined data to and from the reader/writer16 through the antenna 442.

For example, the radio tag 44 is an RFID or the like. In addition, theconfiguration of the radio tag 44 is not limited to a specificconfiguration.

The print region 431 is a region where various images are printed by theprint head 19. In addition, the print region 431 may includeheat-sensitive paper or the like.

Next, the function realized by the data writing device 1 will bedescribed. The function realized by the data writing device 1 isrealized by executing the program stored in the internal memory or thememory 15 by the processor 111.

First, the processor 111 has a function for measuring the radio waveintensity from the radio tag 44 at a plurality of positions.

The processor 111 controls the motor driver 20 to drive the motor 21 toconvey the label roll paper 41. The processor 111 waits until the marksensor 24 detects the mark 45. When the mark sensor 24 detects the mark45, the processor 111 controls the motor 21 to stop conveyance of thelabel roll paper 41. That is, the processor 111 sets the label 43 to aninitial position.

When conveyance of the label roll paper 41 is stopped, the processor 111controls the reader/writer 16 to transmit a predetermined signal to theradio tag 44. When the predetermined signal is transmitted, theprocessor 111 acquires the radio wave intensity of a response from theradio tag 44 using the reader/writer 16. In addition, the processor 111acquires identification information of the radio tag 44 received throughthe reader/writer 16 as a response.

When the radio wave intensity is acquired, the processor 111 controlsthe motor driver 20 to drive the motor 21 and convey the label rollpaper 41 (that is, the label 43) in a smallest movement unit S. When thelabel 43 is moved by S, the processor 111 controls the reader/writer 16to transmit a predetermined signal to the radio tag 44. When thepredetermined signal is transmitted, the processor 111 acquires theradio wave intensity of the response from the radio tag 44 using thereader/writer 16. The processor 111 repeats the above operation untilthe label 43 is moved by the width L of the radio tag 44. By the aboveoperation, the processor 111 measures the radio wave intensity from theradio tag 44 at the plurality of positions in a conveyance direction.

In addition, the processor 111 excludes the radio wave intensity from anadjacent radio tag 44. For example, the processor 111 excludes the radiowave intensity from the adjacent radio tag 44 based on theidentification information from the radio tag 44.

In addition, the processor 111 generates data for a graph of themeasured positions and the radio wave intensities.

FIG. 6 shows an example of the graph. In the example shown in FIG. 6, ahorizontal axis denotes the position of the label 43 (i.e., feed amount)and a vertical axis denotes the radio wave intensity. As shown in FIG.6, an interval between plot points is S. In addition, the points areplotted within the length L of the label 43.

In addition, the processor 111 has a function for calculating thecentral point of a diagram drawn by the graph of the radio waveintensity, i.e., the diagram surrounded by the lines connecting the plotpoints and the axis line for the label feed amount. That is, in FIG. 6,the vertical line including the central point divides the diagram suchthat the divided portions have the same area.

In the example shown in FIG. 6, a line 101 denotes the vertical lineincluding the central point. The line 101 divides the diagram such thatthe areas of the left and right side of the graph coincide with eachother.

In addition, the processor 111 has a function for determining whether apoint (drop point) where the radio wave intensity significantly dropswith respect to the adjacent radio wave intensities is present in apredetermined range from the central point.

For example, the processor 111 determines whether a drop point ispresent in the range of S from the central point. That is, the processor111 determines whether a drop point is present in the range of −S fromthe central point to +S from the central point.

In addition, the processor 111 determines a point where the radio waveintensity is less than a predetermined threshold value T as the droppoint. For example, the threshold value T is the radio wave intensity,at which data can be stably written.

In the example shown in FIG. 6, the processor 111 finds a plot point 102a and a plot point 102 b in the range of S from the central point. Theprocessor 111 determines whether the radio wave intensities of the plotpoints 201 a and 102 b are less than the threshold value T. Here, theprocessor 111 determines that the radio wave intensity of the plot point102 b is less than the threshold value T.

In addition, the processor 111 has a function for setting a writingposition based on the central point and the plot point less than thethreshold value T (i.e., drop point).

The writing position is a position where the antenna 17 is in contactwith the label 43 when the reader/writer 16 writes the data into theradio tag 44. Here, the writing position is a distance, by which thelabel 43 is conveyed from the initial position when the reader/writer 16writes the data into the radio tag 44.

The processor 111 determines the writing position at a positionseparated from the central point by a predetermined distance in adirection opposed to the drop point. For example, the processor 111 setsthe writing position at a position shifted from the central point by Sin the opposite direction.

In the example shown in FIG. 6, the processor 111 sets the writingposition at a point shifted from the central point (the line 101) by Sin the direction opposed to the plot point 102 b. That is, the processor111 sets the writing position at the position denoted by a line 103.

In addition, the processor 111 sets the central point to the writingposition when a drop point is not present in the range of S from thecentral point.

In addition, the processor 111 has a function for writing predetermineddata into the radio tag 44 based on the set writing position.

The processor 111 controls the roller 22 to convey the label 43 suchthat the position of the antenna 17 coincides with the writing position.That is, the processor 111 controls the motor driver 20 to stop themotor 21 or the roller 22 when the label is conveyed to the writingposition after the mark 45 is detected. If conveyance of the label 43 isstopped, the processor 11 controls the reader/writer 16 to writepredetermined data in the radio tag 44 of the label 43. For example, theprocessor 111 controls the reader/writer 16 to transmit a predeterminedwriting command to the radio tag 44.

In addition, the processor 111 may control the reader/writer 16 to writepredetermined data into the radio tag 44 at corresponding timing withoutstopping conveyance of the label 43.

In addition, the processor 11 has a function for printing apredetermined image in the print region 431 of the label 43.

The processor 111 drives the motor 21 to convey the label 43 to theprint head 19. If the label 43 is conveyed, the processor 111 controlsthe print head drive circuit 18 and the print head 19 to print apredetermined image in the print region 431 of the label 43.

In addition, the processor 111 may control the roller 22 to dischargethe label 43, where the predetermined image is printed, to the outside.For example, the processor 111 controls a cutter (not shown in thedrawings) to detach the label 43 from the mount 42 and controls theroller 22 to convey the label to an outlet.

Next, the operation example of the data writing device 1 will bedescribed.

First, the operation example in which the data writing device 1generates the graph will be described. FIG. 7 is a flowchartillustrating the operation example in which the data writing device 1generates the graph.

First, the processor 111 controls the roller 22 to set the label 43 atthe initial position (ACT 11), by detecting the mark 45 through the marksensor 24. When the label 43 is set at the initial position, theprocessor 111 acquires the radio wave intensity from the radio tag 44 ofthe label 43 using the reader/writer 16 (ACT 12).

When the radio wave intensity is acquired, the processor 111 controlsthe roller 22 to convey the label 43 by S (ACT 13). When the label 43 isconveyed by S, the processor 111 determines whether the label 43 hasbeen conveyed by the length L of the label 43 (ACT 14).

Upon determining that the label 43 has not been conveyed by the length Lof the label 43 (ACT 14, NO), the processor 111 returns to ACT 12.

Upon determining that the label 43 has been conveyed by the length L ofthe label 43 (ACT 14, YES), the processor 111 removes the radio waveintensity of different identification information (ACT 15). When theradio wave intensity of the different identification information isremoved, the processor 111 generates data for drawing the graph of theradio wave intensity (ACT 16).

When the data for the graph of the radio wave intensity is generated,the processor 111 ends operation.

Next, the operation example in which the data writing device 1 sets thewriting position will be described. FIG. 8 is a flowchart illustratingthe operation example in which the data writing device 1 sets thewriting position.

First, the processor 111 generates the data for the graph of the radiowave intensity (ACT 21). The operation example of generating the datafor the graph of the radio wave intensity was described above. When thegraph of the radio wave intensity is generated, the processor 111calculates the central point based on the graph (ACT 22). When thecentral point is calculated, the processor 111 determines whether a droppoint is present in the predetermined range from the central point (ACT23).

Upon determining that the drop point is not present in the predeterminedrange from the central point (ACT 23, NO), the processor 111 sets thecentral point to the writing position (ACT 24).

Upon determining that the drop point is present in the predeterminedrange from the central point (ACT 23, YES), the processor 111 determineswhether the drop point is at an upstream side of the central point (ACT25). Upon determining that the drop point is at the upstream side of thecentral point (ACT 25, YES), the processor 111 sets the positionseparated from the central point by S in the downstream direction to thewriting position (ACT 26).

Upon determining that the drop point is not at the upstream side of thecentral point (ACT 25, NO), the processor 111 sets the positionseparated from the central point by S in the upstream direction to thewriting position (ACT 27).

If the central point is set to the writing position (ACT 24), if thewriting position is set to the position separated from the central pointby S in the downstream direction (ACT 26), or if the writing position isset to the position separated from the central point by S in theupstream direction (ACT 27), the processor 111 ends operation.

In addition, the processor 111 may control the roller 22 to convey thelabel 43 itself, instead of the label roll paper 41. For example, theprocessor 111 may control the roller 22 to take out the label 43 from asupply unit for storing a plurality of labels 43 and convey the label43.

In addition, the processor 111 may control the print head 19 not toprint an image on the label 43.

In addition, the processor 11 may control the roller 22 to return thelabel 43 to the upstream side when data is written into the radio tag44.

In addition, the antenna 17 is movable. The processor 111 may control anantenna control mechanism (not shown) to move the antenna 17 to measurethe radio wave intensity of each unit. In addition, the processor 111may control the antenna control mechanism to move the antenna 17 to thewriting position and store predetermined data in the radio tag 44.

The data writing device having the above configuration generates thedata for the graph of the radio wave intensity and calculates thecentral point of the graph. In addition, the data writing devicedetermines the writing position to a position avoiding a drop point,when a drop of the radio wave intensity is present in the predeterminedrange from the central point. As a result, the data writing device canset the writing position to a position where the radio wave intensity ishigh even when a drop of the radio wave intensity is present in thecentral portion of the label. Accordingly, the data writing device canwrite data at a position where the sensitivity of the radio wave fromthe radio tag is high.

Second Embodiment

Next, a second embodiment will be described.

The data writing device 1 according to the second embodiment isdifferent from the first embodiment in that the writing position is setbased on a binarized graph. Accordingly, the other portions are denotedby the same reference numerals and a detailed description thereof willbe omitted.

The configuration example of the data writing device 1 according to thesecond embodiment is equal to that of the first embodiment and thedescription thereof will be omitted.

Next, the function performed by the data writing device 1 will bedescribed. The function of the data writing device 1 is performed byexecuting the program stored in the internal memory or the memory 15 bythe processor 111.

First, the processor 111 has a function for generating data for a graphobtained by binarizing the graph of the radio wave intensity.

The processor 111 compares the radio wave intensity of each positionwith a predetermined threshold value R. For example, the threshold valueR is a radio wave intensity, at which data can be stably written. If theradio wave intensity is equal to or greater than the predeterminedthreshold value R, the processor 111 sets the value of the correspondingposition to true (High). In addition, if the radio wave intensity isless than the threshold value R, the processor 111 sets the value of thecorresponding position to false (Low).

FIG. 9 shows an example of the binarized graph. In FIG. 9, the graph 201is obtained by binarizing the radio wave intensity. As shown in FIG. 9,the values of the graph 201 indicate high or true in a section where theradio wave intensity is equal to or greater than the threshold value R.In addition, the values of the graph 201 indicate low or false in asection in which the radio wave intensity is less than the thresholdvalue R.

Here, the graph 201 has a section 301 and a section 302 as a section(true section) in which the value is true.

In addition, the processor 111 has a function for selecting the truesection for setting the writing position.

First, the processor 111 determines whether a plurality of true sectionsare present. If one section is present, the processor 111 selects thecorresponding true section.

Upon determining that the plurality of true sections are present, theprocessor 111 determines whether a plurality of true sections having alargest width is present. If one true section having the largest widthis present, the processor 111 selects the corresponding true section.

Upon determining that the plurality of true sections having the largestwidth is present, the processor 111 selects a true section close to themark 45. That is, the processor 111 selects the true section such that aconveyance distance to the writing position after detecting the label 43becomes short.

In the example shown in FIG. 9, the processor 111 determines whether aplurality of true sections (sections 301 and 302) is present. Inaddition, since the section 301 is wider than the section 302, theprocessor 111 selects the section 301.

In addition, the processor 111 has a function for setting the centralpoint of the selected true section to the writing position.

The processor 111 calculates the central point of the selected truesection. When the central point is calculated, the processor 111 setsthe calculated central point to the writing position.

In the example shown in FIG. 9, the processor 111 sets the central pointof the section 301 to the writing position.

Next, the operation example of the data writing device 1 will bedescribed.

FIG. 10 is a flowchart illustrating the operation example of the datawriting device 1.

First, the processor 111 generates the data for the graph of the radiowave intensity (ACT 31). When the data for the graph of the radio waveintensity is generated, the processor 111 binarizes the generated graph(ACT 32).

When the generated graph is binarized, the processor 111 determineswhether a plurality of true sections are present (ACT 33). Upondetermining that the plurality of true sections are present (ACT 33,YES), the processor 111 determines whether a plurality of true sectionshaving a largest width is present (ACT 34).

Upon determining that one true sections having the largest width ispresent (ACT 34, NO), the processor 111 selects the true section havingthe largest width (ACT 35).

Upon determining that the plurality of true sections having the largestwidth is present (ACT 34, YES), the processor 111 selects a true sectionclosest to the mark 45 (ACT 36).

Upon determining that one true sections is present (ACT 33, NO), theprocessor 111 selects the corresponding true section (ACT 37).

If the true section having the largest width is selected (ACT 35), if atrue section closest to the mark 45 is selected (ACT 36) or if thecorresponding true section is selected (ACT 37), the processor 111calculates the central point of the selected true section (ACT 38).

When the central point of the selected true section is calculated, theprocessor 111 sets the calculated central point to the writing position(ACT 39). When the calculated central point is set to the writingposition, the processor 111 ends the operation.

The data writing device having the above configuration sets the centralpoint of the section of the radio wave intensity exceeding apredetermined threshold value to the writing position. As a result, thedata writing device can set the writing position to a position avoidingfalling of the radio wave intensity.

In addition, the data writing device sets the central point of thewidest section to the writing position. As a result, the data writingdevice can set the writing position to a position farther from falling.

In addition, the data writing device sets the central point of thesection closest to the mark showing the position of the label to thewriting position. As a result, the data writing device can convey thelabel to the writing position by a least conveyance amount afterdetecting the mark.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. A data writing device comprising: a rollerconfigured to convey a plurality of labels each including a radio tagalong a predetermined path; a reader/writer configured to wirelesslycommunicate with a radio tag; and a controller configured to control theroller to convey the labels and control the reader/writer to acquire aplurality of radio wave intensities from a radio tag included in one ofthe labels at different positions of said one of the labels along thepredetermined path as the labels are conveyed, generate data forplotting a graph of the acquired radio wave intensities with respect tothe different positions of said one of the labels along thepredetermined path, and determine, as a writing position for the radiotag included in said one of the labels, a position along thepredetermined path based on the plotted graph of the radio waveintensities, the radio wave intensity at the writing position beingequal to or greater than a threshold value according to the plottedgraph.
 2. The data writing device according to claim 1, wherein thecontroller is configured to determine the writing position by groupingthe different positions into one or more groups and selecting thewriting position from one of the groups.
 3. The data writing deviceaccording to claim 2, wherein the controller is configured to select theone of the groups including a greatest number of the positions at whichthe radio wave intensities are equal to or greater than the thresholdvalue.
 4. The data writing device according to claim 2, wherein thecontroller is configured to select the one of the groups including theposition closest to a top position of said one of the labels.
 5. Thedata writing device according to claim 1, further comprising: a sensorconfigured to detect a top position of each of the labels by reading amark on the label.
 6. The data writing device according to claim 5,wherein each of the labels has a first surface where an image is printedand a second surface where the mark is indicated.
 7. The data writingdevice according to claim 1, wherein the controller is configured tocalculate a central point of a diagram on the graph, formed by aplurality of lines each connecting adjacent plotted points of the radiowave intensities and an axis line of the positions, and determine thewriting position based on the calculated central point.
 8. The datawriting device according to claim 7, wherein when there is a drop pointin the graph where the radio wave intensity is less than the thresholdvalue within a predetermined range from the central point, the writingposition is separated from the central point by a predetermined distancein a direction opposed to the drop point.
 9. The data writing deviceaccording to claim 1, further comprising: an antenna configured to emitradio waves toward the predetermined path.
 10. The data writing deviceaccording to claim 9, wherein a surface of each of the labels that facesthe antenna does not include an area where an image is printed.
 11. Amethod performed by a data writing device, the method comprising:conveying, by a roller, a plurality of labels each including a radio tagalong a predetermined path; acquiring, by a reader/writer, a pluralityof radio wave intensities from a radio tag included in one of the labelsat different positions of said one of the labels along the predeterminedpath as the labels are conveyed; generating data for plotting a graph ofthe acquired radio wave intensities with respect to the positions ofsaid one of the labels along the predetermined path; and determining, asa writing position for the radio tag included in said one of the labels,a position along the predetermined path based on the plotted graph ofthe radio wave intensities, the radio wave intensity at the writingposition being equal to or greater than a threshold value according tothe plotted graph.
 12. The method according to claim 11, wherein thedetermining comprises grouping the different positions into one or moregroups and selecting the writing position from one of the groups. 13.The method according to claim 12, wherein the selecting comprisesselecting the one of the groups including a greatest number of thepositions at which the radio wave intensities are equal to or greaterthan the threshold value.
 14. The method according to claim 12, whereinthe selecting comprises selecting the one of the groups including theposition closest to a top position of said one of the labels.
 15. Themethod according to claim 11, further comprising: detecting, by asensor, a top position of each of the labels by reading a mark on thelabel.
 16. The method according to claim 15, wherein each of the labelshas a first surface where an image is printed and a second surface wherethe mark is indicated.
 17. The method according to claim 11, wherein thedetermining of the writing position includes calculating a central pointof a diagram on the graph formed by a plurality of lines each connectingadjacent plotted points of the radio wave intensities and an axis lineof the positions on the graph, and determining the writing positionbased on the calculated central point.
 18. The method according to claim17, wherein when there is a drop point in the graph where the radio waveintensity is less than the threshold value within a predetermined rangefrom the central point, the writing position is separated from thecentral point by a predetermined distance in a direction opposed to thedrop point.
 19. The method according to claim 11, further comprising:emitting, by an antenna, radio waves toward the predetermined path. 20.A non-transitory computer readable medium storing a program causing acomputer to execute a method of writing data into a radio tag, themethod comprising: conveying, by a roller, a plurality of labels eachincluding a radio tag along a predetermined path; acquiring, by areader/writer, a plurality of radio wave intensities from a radio tagincluded in one of the labels at different positions of said one of thelabels along the predetermined path as the labels are conveyed;generating data for plotting a graph of the acquired radio waveintensities with respect to the different positions of said one of thelabels along the predetermined path; and determining, as a writingposition for the radio tag included in said one of the labels, aposition along the predetermined path based on the plotted graph of theradio wave intensities, the radio wave intensity at the writing positionbeing equal to or greater than a threshold value according to theplotted graph.